Divisional planes

from The Collaborative International Dictionary of English v.0.48

Divisional \Di*vi"sion*al\, a.
   That divides; pertaining to, making, or noting, a division;
   as, a divisional line; a divisional general; a divisional
   surgeon of police.
   [1913 Webster]

   {Divisional planes} (Geol.), planes of separation between
      rock masses. They include joints.
      [1913 Webster]